h1

Initial Test Of Vertical Jump Measurement Methods

November 18, 2007

Continuing the discussion from my last post (Double Axel Barrier), I’ve been able to run two tests so far with mixed results.  Recall that I’m trying to determine if flight time measurements made using video analysis software such as Dartfish or Pro-Trainer (a low cost Dartfish substitute) can be used to estimate jump height.

As stated in previous posts, sufficient flight time is a critical component for figure skating jumps.  For example, in order to get enough rotation to land a clean double axel, the minimum flight time needs to be about 0.45 seconds.  Based on some physics calculations (basic projectile motion), I’ve been estimating the required height at 10.5 inches (0.467 seconds).

My ultimate goal is to see what percentage of the female population is physically capable of landing a double axel.  To do that I’ll need to correlate the flight times with standard vertical jump statistical data.

The first part of the test is as follows:
1. Skater stands next to wall and reaches up and makes a mark with one finger (using chalk or washable marker).
2. Skater stands on tip toes near the wall and makes another mark with same finger.
3. Then skater fully bends and jumps up off two feet as high as possible, slapping the wall and making another mark.
4. Step 3 is repeated until skater has a consistent pattern on the wall of maximum jump height.
5. The standing mark is considered the baseline.  The tip toe mark and the maximum jump height are measured from the baseline.

That gives us our “standard” vertical jump measurement.  This is the most common method used for measuring vertical jump.  Statistical data is available based on this measurement method as discussed in a recent post.  (The tip toe data is necessary for correlating with flight times and is not part of the standard test or available statistical data.)

Next, the video method is used.  For the video method, the capture software is turned on and:
1. The skater jumps multiple times facing sideways to the camera.
2. The skater jumps multiple times off one foot, using a natural “leg through and lift” technique.
3. The capture is stopped and the flight time for all the jumps is found.  (As discussed in post Are Figure Skater’s Projectiles?, the flight time is measured from the first frame the foot completely leaves the ground until the first frame when the foot touches the ground).

I performed this test with 2 skaters.

Skater A:
Baseline to tip toes:  2.9 inches
Maximum vertical jump off two feet at wall:  10.5 inches
Maximum flight time off two feel on video:  0.450 seconds (video shows flat footed landing)
  Corresponding jump height estimate from video:  9.8 inches
Maximum flight time off one foot on video:  0.351 seconds
  Corresponding jump height estimate from video:  5.9 inches

Skater B:
Baseline to tip toes:  3.1 inches
Maximum vertical jump off two feet at wall:  13.4 inches
Maximum flight time off two feel on video:  0.450 seconds (video shows flat footed landing)
  Corresponding jump height estimate from video:  9.8 inches
Maximum flight time off one foot on video:  0.450 seconds
  Corresponding jump height estimate from video:  9.8 inches

These results are clearly not conclusive.  Each skater only made three attempts for each measurement and the measurements were not always tightly clustered.  For example, Skater A had two foot flight times of 0.417, 0.451, and 0.433 seconds while Skater B had two foot flight times of 0.450, 0.434, and 0.451 seconds.  Skater A had one foot flight times of 0.317, 0.334, and 0.351 seconds while Skater B had two foot flight times of 0.400, and 0.450 seconds.

In future tests, each skater will perform more attempts to get a better estimate of the maximum.  When I have more data,  I’ll see if I can correlate the results and add in factors for take-off from tip toes and landing flat footed.

Also note, that some skaters will be able to jump just as high (or even higher) off one leg versus two, while other skaters clearly lose significant height jumping off only one leg.

I’m not sure this will be useful to you yet, but it just keeps you up to date on some of my testing.

Trevor

Advertisements

3 comments

  1. I have been involved in testing all types of athletes for about 7 years. I found that there is huge variation in testing Left vs Right. (Also from one test to another with the same individual over the course of 2 years)-it usually correlates to what jumps they have been working on. Also, there seems to be minimal correlation between what someone can do with both legs and with what they can do with one leg.(Stability and core factors) I use the Vertec and your method. I also know all of the ways to cheat! There are some norms available if you contact Athlete’s Republic.


  2. This sounds like a pretty intensive task you’re taking on! I was looking for information about vertical jumping and I came across this page. Good luck with your goal…you probably already achieved it by now!

    -John


  3. […] the original: Initial Test Of Vertical Jump Measurement Methods Posted in General Tags: baseline, dartfish, dartfish substitute, double-axel, feel-on-video, […]



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: